Exemplary embodiments of the invention relate to a method and a device for detecting the opening state of a garage door or the like, such as a door that restricts entry by a vehicle.
The opening state of garage doors cannot be reliably detected using the ultrasound sensors of parking systems that are installed in conventional vehicles, for example in cars. Although ultrasound sensors have a range of approximately 1 m in normal driving operation and a range of approximately 5-6 m at low speeds, as are common when parking, they only provide reliable feedback up to a height of approximately 50 cm due to their installation height in parking systems. In particular for automated parking, however, it is very important to determine whether a garage door is open wide enough for the vehicle to drive into the garage without being damaged.
Cameras which detect the road in front of the vehicle in driving operation and, for example, record the road markings or road signs are increasingly also being used in vehicles. These conventional cameras have difficulty correctly classifying the door, i.e., recognizing it as a garage door and recognizing the opening state thereof.
For example, radar sensors used for measuring the distance from the vehicle in front provide inaccurate results for garage doors due to reflections from the open space behind the door, or do not provide an echo of the radio waves emitted by the radar that can be definitively located.
A LiDAR, in which laser beams are used for optical distance measurement, usually does not provide a large enough opening angle, meaning that it likewise has significant limitations for detecting doors that open upwards.
Using conventional techniques, the opening state of garage doors that open upwards can only be unreliably determined. For example, it is also difficult to detect if a garage door has stopped halfway up and is thus preventing entry. Doors which slide sideways and are not solid may likewise provide an unreliable echo.
In this context, reference may also be made to US 2014/0118111 A1. This document describes an alarm system which alerts the person responsible to close the garage again if a door is unintentionally open. Here, various physical methods are described for identifying the open door. They are based, for example, on a change in the brightness and noise level when the door is open compared with when the door is closed, on an RFID chip on the door or on an image comparison of the stored image of the open door and the closed door. These methods require a complex apparatus and/or can only be used for the specific known door. Other principles measure the distance between the door and the parked vehicle using a laser or ultrasound. They are more flexible in relation to the door, but like the above-mentioned method involve the problem whereby they cannot detect a half-open door or non-solid doors, such as gates.
Systems with which the region in front of a vehicle can be illuminated by means of headlights are known from the prior art.
DE 10 2011 119923 A1 discloses an intelligent lighting system intended to act as a navigation and operating aid for vehicles. In this system, the dimensions and the radii of action of the vehicle and the components thereof are projected directly onto the road in addition to the normal illumination. This visualization of the vehicle width is intended to create a kind of warning system, which is also intended to be helpful for narrow thoroughfares, such as gateways and garage entrances. Once the boundary beams are visible on the entry boundary, for example the walls to the left and right of a garage door, this indicates a potential collision to the driver of the vehicle. However, this known lighting system does not make it possible to detect the opening state of a garage door, since the vehicle predominantly projects onto the ground in front of the vehicle. In addition, it is not possible to automatically detect the opening state using this system.
DE 10 2015 224 792 A1 discloses a method for operating a headlight of a motor vehicle comprising at least one actuatable and light-emitting headlight element. The headlight element of the headlight generates a light distribution that is monitored by a camera. The camera generates image data, by means of which an actual operating state of the headlight is determined. An existing functional limitation of the headlight is determined from the deduced actual operating state compared with an intended target operating state. The camera is integrated in the motor vehicle and is arranged behind the windscreen of the motor vehicle, and, for example, is integrated in a rearview mirror device. Using the known method, reduced functionality of a headlight element can be determined during the journey and appropriate measures can be taken. However, this known method does not make it possible to detect the opening state of a garage door, since only the headlight itself is monitored with regard to its functionality.
The two Chinese documents CN 105 222 752 A and CN 203 094 055 U describe methods in which unevenness in the surface of a road can be detected by means of a line pattern projected onto the road. This is advantageous in that a 3D image of the road surface can ultimately be produced using images taken by a 2D camera.
Reference can also be made to DE 103 36 681 A1 as additional prior art, which document describes a method for the targeted illumination of an object detected in the surroundings of a vehicle. A complex headlight is used for this purpose, which is capable of directing its light beam towards the object to be illuminated in a targeted manner.
The problem addressed by the present invention is that of providing a method and a device that make it possible to reliably detect the opening state of a garage door or the like, such as a door that restricts entry by a vehicle.
In the method, a predetermined light pattern is accordingly generated and projected onto the door. The light pattern projected onto the door is detected and compared with the predetermined light pattern. Information signals are generated according to the differences between the detected light pattern and the predetermined light pattern, the differences determining the opening state of the door. Using the method according to the invention, by projecting and observing light patterns on the door to be detected, it is possible to detect, in a simple manner, whether the door is closed, partially open or completely open. In this case, a predetermined pattern is compared with the pattern that is actually detected.
In order to identify partially open regions of the door, regions of the detected light pattern can be detected that have changed compared with the predetermined light pattern. In this case, parts of the predetermined light pattern in the at least partially open regions do not appear, do not completely appear, or appear distorted in the detected or observed light pattern, since here the predetermined light pattern is not projected onto part of the garage door.
In this case, the predetermined light pattern has an array of identical light objects that have the same geometry and surface area. This arrangement makes it possible to easily compare the predetermined light pattern with the detected light pattern, since differences are clearly visible.
The opening process of the door can also be detected by detecting the light pattern projected onto the door and comparing the detected light pattern with the predetermined light pattern continuously or repeatedly. A change in the number of detected light objects and the surface areas of the light objects is analyzed over time here.
In the device, a control apparatus is provided for generating a predetermined light pattern and a headlight apparatus is provided for projecting the predetermined light pattern onto the door. A camera apparatus detects or observes the light pattern projected onto the door. The control apparatus compares the light pattern detected by the camera apparatus with the predetermined light pattern and outputs information signals according to the differences between the detected light pattern and the predetermined light pattern, the differences determining the opening state of the door. Using the device according to the invention, by projecting and observing light patterns on the door to be detected and on the space therebehind, it is possible to detect, in a simple manner, whether the door is closed, partially open or completely open. In this case, a predetermined pattern is compared with the pattern that is actually detected.
According to a preferred embodiment, the headlight apparatus may comprise at least one projection-enabled headlight in the form of a grid-like light source or the like equipped with LED chips that can be individually actuated by the control apparatus. A headlight of this type is also known as a multibeam LED headlight, which can project a focused light pattern onto a surface, for example a garage door. What are known as laser headlights can also be used. This light pattern can be easily detected by the camera apparatus and can be easily processed in the control apparatus, meaning that the distance from the projection surface can be reliably determined.
In a further embodiment, the headlight apparatus may comprise infrared diodes (IR diodes) and the light pattern may be projected in the infrared wavelength range. IR light is invisible to the human eye, and therefore the opening state of the door can be detected without being noticed by observers, and also nobody is dazzled unnecessarily. Alternatively, what is known as a time of flight (TOF) measurement is, for example, also possible using a TOF camera, in which a propagation time technique is carried out by means of laser scanning, similarly to a Flash LiDAR.
A display apparatus may be provided inside the vehicle on which the opening state of the door is displayed to the driver of the vehicle based on the information signals generated by the control apparatus. This may be acoustic and/or graphic. Here, the display device assists the driver when parking in the garage and/or when driving through the door.
In another, advantageous embodiment, the control apparatus may be connected to a fully or partially automatic parking system of the vehicle. Based on the information signals generated by the control apparatus, the opening state of the door may be used for controlling the process of parking the vehicle. For example, by means of what is known as a remote parking pilot, a vehicle equipped with ultrasound parking sensors can be parked remotely using a smartphone. For this remote parking in a garage, it is important that the system takes into account the opening state of the garage door.